Lubricating oil production



C. J. EGAN ETAL LUBRICATING OIL PRODUCTION Jan, 23, 1968 Filed Aug. 23,1966 LIGHT 35 NEUTRAL 22 23 as HEAVY NEUTRAL SOLVENT DEWAX .22 STOCK V G1 :7 l

63 HYDROCRACKED 2 53 O LIGHT 53 NEUTRAL 49 52 HEAVY 48 5o VNEUTRALSOLVENT 54 DEWAX 57 55 \57. STOCK 55 IN V ENTORS CLARK J. EGANISOMERIZED ROBE T J. WHITE WAX . BY m o-u ATTORNE s United States PatentLUBRICATING OIL PRODUCTION Clark J. Egan, Piedmont, and Robert J. White,Pinole, Califi, assignors to Chevron Research Company, San

Francisco, Calif., a corporation of Delaware Continuation-impart ofapplications Ser. No. 548,075, May 6, 1966, and Ser. No. 477,597, Aug.5, 1965. This application Aug. 23, 1966, Ser. No. 574,353

6 Claims. (Cl. 208-60) ABSTRACT OF THE DISCLOSURE Lubricating oils areproduced by hydrocracking a heavy oil feed, separating hydrocracked waxfrom a hydrocracked lubricating oil portion of the products, andhydroisomerizing the hydrocracked wax using an active reformingcatalyst. An isomerized lubricating :oil fraction so produced can bedewaxed separately, to recover ultrahigh VI isomerized lube oil, or inadmixture with a hydrocracked lubricating oil portion. An additionalhydrogenation step may precede and/ or follow the hydroisomerizationstep.

Cross references This application is a continuation-in-part of copendingapplication Ser. No. 477,597, filed Aug. 5, 1965, and acontinuation-in-part of copending application Ser. No. 548,075, filedMay 6, 1966, in turn a continuation-in-part of said Ser. No. 477,597.

This invention relates to processes comprising catalytic hydroconversionof heavy oils to produce lubricating oils. More particularly, theinvention provides a new process for producing lubricating oil ofcontrollable quality as a byproduct of hydroconversion of heavy oils.

Hydrocarbon oils to be suitable for use as lubricants are generallyrequired to be sufficiently high boiling to have low volatility and ahigh flash point. Superior lubricating properties are obtained if theoil is composed primarily of saturated hydrocarbons comprising paraflinsand cycloparaffins, with a minimum content of aromatics. The oils arerequired to flow freely, and thus generally must have a pour point notin excess of about +35 F., and more usually pour points of +1S F., F.,or 0 F. or lower are specified. Many other oil products not designed foruse as lubricants, spray oils for example, desirably have these sameproperties of low volatility, high flash point, high parafiin content,and low pour point.

High quality lubricating oils, for example high viscosity index oils,command a premium price in the market place, but demand is not great. Itis known that high VI lube oils can be produced from lower VI heavy oilsby hydrocracking directly. Heretofore, however, to obtain the desiredhigh quality product it was necessary either to start with a highquality feedstock or else to accept a low yield of high quality product.Thus, methods of hydrocracking low VI oils to produce high VI oilsrequire operating the hydrocracker at special conditions carefullytailored to the feed properties in order to obtain the particulardesired properties in the lube oil, which is only a minor product. Suchprocesses have not gained wide commercial acceptance for this reason. Asa practical matter, a refiner has to operate his major facilities asneeded to obtain the desired yields and properties of the majorproducts.

In one aspect, the present invention provides a method, comprising acombination of treating steps including by drocracking, whereby a wideselection of low, medium, high, and ultrahigh viscosity indexlubricating oils can be produced as desired, while operating thehydrocracking step as needed or desired to obtain optimum economics withrespect to conversion of unwanted heavy oils to those distillate fuelproducts for which demand is greatest.

In the aforementioned copending application Ser. No. 477,597, there isdisclosed the catalytic hydrocracking of heavy oil to obtain lownitrogen content heavy oil which is catalytically hydroisomerized andhydrocracked to produce low pour point lubricating oil without dewaxing.In the aforementioned copending application Ser. No. 548,- 075, it isdisclosed that the catalytic hydroisomerization of nitrogen-free waxyoils is made more selective for isomerization with less hydrocrackingwhen the waxy oil is prehydrogenated. Although it is shown possible bythese methods to make lubricating oils having pour points as low asthose obtainable by a solvent dewaxing, the cloud points of the heaviestproduct oils were sometimes unsatisfactory. Also, stability problemswere sometimes encountered in the product such that a mild finishinghydrogenation was needed. Conditions in the preparation of the feed hadto be controlled so as to provide for the catalytic hydroisomerizationstep an oil having a low nitrogen content.

It has now been found that high quality lubricating oils can be preparedby catalytic hydroisomerization of Wax separated from heavy hydrocrackedoil. In accordance with the invention a heavy oil feed boiling at leastpartly above 900 F. is hydrocracked in a catalytic hydrocracking Zoneusing a sulfactive hydrocracking catalyst, and the oil effluent thereofis separated into fractions including a distillate fuel and a higherboiling hydrocracked lube oil boiling range fraction. The saidhydrocracked lubricating oil boiling range fraction is dewaxed to obtaina hydrocracked wax fraction of low nitrogen content. At least a portionof the hydrocracked wax fraction is hydroisomerized in ahydroisomerization zone using an active reforming catalyst, and the oileilluent thereof is separated into fractions including a distillate fueland an isomerized lube oil boiling range fraction. Desirably, conversionof the wax to lubricating oil by hydroisomerization is incomplete, andat least a high boiling portion of the isomerized material is dewaxed,e.g. by the same techniques as used with the hydrocracked oil, to obtainadditional dewaxed isomerized lube oil and an isomerized wax.

In the invention, the hydrocracking process from which the hydrocrackedwax is derived can be operated to produce the desired yield and qualityof distillate fuel products without trying to regulate the quality oflubricating oil obtainable by the hydrocracking step. For example, arelatively low viscosity index lubricating oil can be recovered from thedewaxing of the heavy hydrocracked oil, and the operation of thehydroisomerization step applied to the wax, involving treatment of amuch smaller quantity of material than the hydrocracking step, can becontrolled to produce a relatively higher viscosity index oil which canbe 'blended with the low viscosity index oil to provide a lube oil ofdesired intermediate viscosity index.

A hydrocracked wax of low sulfur and nitrogen content is needed for thecatalytic hydroisomerization step. However, it is not necessary tocontrol the hydrocracking to get down to any particular low nitrogencontent in the heavy hydrocracked oil. The dewaxing can include deoilingof the wax, if necessary, to remove most of the oil containing thenitrogen and sulfur compounds and provide hydrocracked wax of sufficientpurity in most instances. Also, the oil to be dewaxed, or the wax, canbe further treated to remove nitrogen and sulfur compounds moreeconomically in a separate step as compared to attempting to obtain therequired purity directly by hydrocracking. It is necessary, however,that the hydrocracked wax to be catalytically hydroisomerized be derivedfrom hydrocracking of a heavy oil under conditions causing a largehydrogen consumption and substantial conversion to lower boilingdistillates. The wax present in the heavy hydrocracked oil, referred toherein as hydrocracked wax, differs substantially from wax separated byconventional solvent dewaxing of straight run lubricating oil fractions.In particular, the hydrocracked wax is of the microcrystalline type andincludes a much larger proportion of isoparaffins relative to normalparafiins as compared to straight run wax.

The single figure in the attached drawing illustrates schematically flowpaths and treating steps which can be used in carrying out the processof this invention. Briefly, as shown in the drawing, a heavy oil feed inline 11 and hydrogen in line 12 pass via line 13 to hydrocracking zone14 wherein the oil is contacted with a sulfactive hydrocracking catalystat hydrocracking conditions. At least the hydrocracked oil eifiuent inline 15 is separated as by distillation in zone 16 to obtain a lightfraction in line 17, distillate fuel fractions in lines 18 and 19, and abottoms hydrocracked fraction in line 20. A portion of the hydrocrackedbottoms may be withdrawn through line 21. All or a portion of thehydrocracked bottoms fraction may pass via line 22 to solvent dewaxingzones 23. Alternately, all or a portion of the hydrocracked bottoms maypass via line 24 to further purification treatment such as solventextraction in zone 25. Where solvent extraction is used, the solventextract mixture in line 26 is separated in zone 27 into a solventfraction for reuse in line 28 and an extract fraction in line 29. Thesolvent treated oil in line 30 then passes to the dewaxing zone 23. Fromthe dewaxing there is obtained a dewaxed hydrocracked oil in line 31 anda hydrocracked wax fraction in line 32. The dewaxed hydrocracked oil ofline 31 may be separated as by distillation in zone 33 into fractionssuch as a light neutral lube oil in line 34, a heavy neutral lube oil inline 35, and a bright stock in line 36 if the original heavy oil feedwas sufficiently high boiling, such as a deasphalted residuum. A portionof the hydrocracked wax in line 32 may be withdrawn through line 37, butat least a portion thereof is passed via line 38 and line 40 withhydrogen added via line 39 into hydroisomerization zone 41. Inhydroisomerization zone 41 the oil and hydrogen contact an activereforming catalyst at hydroisomerization conditions of elevatedtemperature and pressure. At least the oil efiluent of thehydroisomerization in line 42 is separated as by distillation in zone 43to obtain a light fraction in line 44, a distillate fuel fraction inline 45, and an isomerized bottoms fraction in line 46. All or a portionof the waxy isomerized oil in line 46 may be passed via line 47 to thesolvent dewaxing zone 23. Alternately, all or a portion of the waxyisomerized oil may pass via line 48 to separate solvent dewaxing zone49. From the dewaxing zone 49 there is obtained a dewaxed isomerized oilin line 50 and an isomerized wax fraction in line 51. The dewaxedisomerized oil may be separated as by distillation in zone 52 to obtainfractions such as a light neutral lube oil in line 53, a heavy neutrallube oil in line 54, and a bright stock in line 55. All or a portion ofthe isomerized wax fraction of line 51 may be withdrawn through line 56.All or a portion may instead be recycled via line 57 to thehydroisomerization zone 41.

More specifically, the heavy oil feed treated in accordance with theinvention is a high pour point heavy oil boiling in the lubricating oilrange, which must boil mostly above 700 F. More desirably, the oil feedboils mostly above 800 F. and at least partly above 900 F. A preferredfeed is at least as heavy as a straight run vacuum gas oil, and thesingle most preferred feed is a deasphalted residual oil. The oil isrequired to be nonasphaltic because the asphaltenes, being polynucleararomatic-type compounds, interfere with the conversion of parafiins inthe process of the invention and also tend to rapidly deactivate thecatalysts used. The deasphalting treatment applied in preparing thepreferred feed may be the type of deasphalting used in preparing heavycatalytic cracked feedstoeks, i.e., treatment with a light hydrocarbonsolvent such as propane, butane, pentane, or mixtures thereof, at ornear the critical point of the solvent. The treatment may be such as torecover as feed the entire so-called maltene fraction, comprising oiland resins, rejecting only the asphaltenes. The deasphalted oil feedtreated in accordance with the invention will have a high pour point ofabove +35 F., and more usually of at least 50 F. Thus, a deasphalted oilfeed will contain sufficient high melting parafiins such that at leastabout 10 weight percent of the feed would have to be separated as wax toobtain a pour point of 0 F. by known solvent dewaxing methods.

In the hydrocracking step of the present invention the heavy oil feedand hydrogen are passed through a reaction zone to contact therein asulfactive hydrocracking catalyst at elevated temperature and pressureat a space velocity providing sufficient contacting time to accomplishthe desired conversion. Conditions used include temperatures of 650900F., more desirably 700850 F., and pressure of at least about 1000p.s.i.g., which may range upwards of 5000 p.s.i.g., the preferred rangebeing 1500- 4000 p.s.i.g. The throughput of hydrogen-rich gas, which maybe recycled, should be at least 1,000 s.c.f./bbl. of feed, more usually2,000-20,000 s.c.f./bbl. The space velocity is generally in the range0.210 volumes of oil per volume of catalyst per hour (LHSV), usually0.3-3 LHSV.

The catalyst used in the hydrocracking may be of the sulfactivehydrogenation type commonly used for desulfurization anddenitrification. Suitable catalysts include combinations of the Group VIand Group VIII metals, oxides, or sulfides, associated with porousrefractory oxide carriers. Most suitable metals are nickel or cobalt incombination with molybdenum or tungsten, as sulfides. The refractoryoxide may be alumina, but usually, to provide more hydrocrackingactivity, there is employed a comibnation of alumina with silica,magnesia, titania, and like materials, or combinations of such otheroxides, for example silica-magnesia. Such catalysts can be prepared in avariety of ways, including preparing the porous carrier first and thenimpregnating it with solutions of the metal compounds which are laterconverted to metal oxides by calcining. Particularly good catalysts foruse in the hydrocracking step can be prepared by coprecipitation orcogelation techniques wherein all of the components are initiallysupplied as dissolved compounds in aqueous solutions, and coprecipitatedtogether. The conditions in the hydrocracking step may be such as tosubstantially eliminate organic sulfur compounds by conversion to H Sand to substantially eliminate organic nitrogen compounds by conversionto NH The nitrogen conversion is the most difficult to accomplish, andaccordingly if conditions are sufficiently severe to reduce the organicnitrogen content to about 10 ppm. or lower, the organic sulfurconcentration will also have been reduced to about 50 parts per millionor lower unless the impure oil feed has an unusually high sulfurcontent, and a substantial portion, at least about 30 volume percent, ofthe oil will be hydrocracked to distillates boiling below 900 F.

In the present invention the hydrocracking step need not be regulated toobtain a particular low nitrogen or sulfur concentration in thehydrocracked lubricating oil boiling range fraction produced. Instead,the hydrocracking operation may be, and preferably is, regulated withreference to achieving a desired degree of hydrocracking conversion todistillate fuels. Thus, the operation can be controlled to obtain adesired API gravity in the whole liquid effluent of the hydrocrackingwhich is higher than the API gravity of the heavy oil feed by apredetermined amount. Adjustment of the operating conditions with timeonstream to compensate for gradual catalyst aging can be with referenceto maintaining the desired product gravity, in which case the organicnitrogen and sulfur concentrations in the hydrocracked lubricating oilfraction produced may gradually increase with time onstream if thecatalyst activity for desulfurization and/or denitrification declinesmore rapidly than the catalyst activity for hydrocracking. Since theattaining of the desired results in the hydroisomerization of waxseparated from the hydrocracked lubricating oil boiling range fractiondepends in part on the wax having properties peculiar to a hydrocrackedwax fraction, it appears important that there be substantialhydrocracking and hydrogen consumption in the hydrocracking step. Itappears that at least about percent conversion of the feed todistillates lower boiling than the feed is needed to obtain the desiredwax properties. With residual oil feeds conversion should be at leastvolume percent to distillates boiling below 900 F. and may range upwardsof 80 percent. The conversion is accompanied by the consumption ofsubstantial amounts of hydrogen, amounting usually to above 500 standardcubic feet per barrel of oil and usually 750 s.c.f./bbl. or more.

Various forms of apparatus and manipulative techniques which can be usedin carrying out the hydrocracking step are well known in the art, andaccordingly no particular equipment arrangement is specified in thehydrocracking step of the attached drawing. Most conveniently, the heavyoil and hydrogen-rich gas are passed together downward through fixedbeds of catalyst particles in a high pressure reactor at the reactionconditions, the efliuent is cooled to separate the normally liquidportion of the oil from hydrogen-rich gas which is recirculated, and theliquid oil portion represented by line 15 of the drawing is fractionatedinto various streams as shown by zone 16. Distillate fuels producedboiling entirely below the lubricating oil boiling range, i.e. belowabout 650-750 F., are separated from a higher boiling hydrocrackedlubricating oil boiling range fraction, i.e. boiling entirely aboveabout 650-750 F. In accordance with the invention at least a portion ofsuch a lubricating oil boiling range hydrocracked fraction is dewaxed toobtain a hydrocracked wax fraction for subsequent treating in theprocess.

The dewaxing involves physically separating wax from the oil, which maybe done by a variety of known procedures. Thus, the oils may be cooledto a low temperature sufficient to crystallize out the Wax, and the waxcan then be physically separated by filtration, centrifugation, or likemethods. More commonly, solvent dewaxing is employed wherein a solventsuch as a mixture of methylethyl ketone and benzene is added, whichpreferentially dissolves the nonwaxy hydrocarbons and lowers the oilviscosity without appreciably lowering the crystallization temperatureof the wax. Other methods involving forming complexes with the waxmolecules, such as in the urea adduction process, can also be used. Ingeneral, the dewaxing is regulated to obtain a specified pour point inthe dewaxed oil usually of 20 F. or lower.

The dewaxed oil, in line 31 of the drawing, is usually separated byvacuum distillation as in zone 33 into various grades of lubricating oilon the basis of viscosity and boiling range. Thus, there may be obtainedfor example in line 34 a light neutral lube oil base stock having aviscosity of 150 SSU at 100 F., in line 35 a heavy neutral with aviscosity of 380 SSU at 100 F., and in line 36 a bright stock having aviscosity of 120 SSU at 210 F. In some cases it may be desirable toseparate the broad boiling range hydrocracked lubricating oil fractioninto the various viscosity grades prior to dewaxing if it is foundadvantageous to use different dewaxing conditions to obtain the desiredpour points. Lubricating oil produced by either method may have aviscosity index ranging from low to high, depending on the hydrocrackingconditions used, and may require further treatment to improve color andstability, the hydrocracking step not having been controlled withreference to obtaining particular lubricating oil properties.

The hydrocracked wax of line 32 may comprise the socalled slack waxcontaining entrained oil first separated by filtration in the dewaxingof the oil, if the hydrocracking of the heavy oil feed was carried outat conditions sufiiciently eliminating organic nitrogen and sulfurcompounds from the oil such that the small amount re maining in the oilentrained with the slack wax does not provide a nitrogen content above10 p.p.m. If the slack wax contains above about 10 p.p.m. nitrogen, orabove about 50 p.p.m. sulfur, it should be deoiled to remove the oil,which contains most of the organic sulfur and nitrogen compounds, ifthis will provide a sufficiently low concentration of thesecontaminants. In cases where the heavy oil feed was highly contaminatedwith nitrogen and/ or sulfur and the hydrocracking conversion did notsufficiently eliminate such compounds, it will be necessary to furthereliminate them from the wax. For example, a portion of the waxyhydrocracked oil boiling in the lubricating oil range, in line 24-, maybe treated with an acid solvent such as sulfuric acid or HP in zone 25to extract the organic nitrogen compounds therefrom. Where HP is used,the acid-oil sludge in line 26 may be separated into a reusable HFfraction in line 28 and an extract oil frac tion rich in sulfur andnitrogen compounds in line 29, which is withdrawn. Such a treatment ispreferably applied to the portion of the whole hydrocracked bottoms fromwhich the hydrocracked wax and hydrocracked lubricating oil are to beseparated, as it also improves the quality of the lubricating oilfraction besides purifying the wax fraction.

A portion of the clean hydrocracked wax in line 32 may be withdrawnthrough line 37 if, for example, the amount of hydrocracked lubricatingoil of relatively low viscosity index which is salable substantiallyexceeds the need, either directly or as a blending stock, for higherviscosity index lubricating oil which can be produced from thehydrocracked wax by the subsequent hydroisomerization. At least aportion of the hydrocracked wax is hydroisomerized in thehydroisomerization zone to produce high viscosity index lubricating oil.In the hydroisomerization zone the hydrocracked wax is contacted with anaphtha reforming catalyst at conditions including temperatures of700-900 F., preferably 750-850 F.; pressures of 500-5000 p.s.i.g., moreusually 1000-3000 p.s.i.g.; hydrogen-rich gas throughput rates greaterthan 1,000 standard cubic feet per barrel of oil, generally 2,000 20,000s.c.f./bbl.; and contact times in terms of liquid hourly space velocityof from 0.2-10, preferably 0.33 LHSV. The conditions are such that atleast about 10 weight percent of the wax entering the hydroisomerizationreaction zone is hydrocracked to lower boiling distillates. it isdesirable to minimize hydrocracking and to favor hydroisomerization toproduce high viscosity index lubricating oil without unduly lowering theviscosity, but it appears desirable at least with wax derived fromresidual oil feeds that the conversion be at least about 20 percent todistillates boiling below 750 F. to obtain a high per pass yield oflubricating oil after dewaxing. If it is desired to dispense withsolvent dewaxing of the hydroisom erized oil produced from thehydrocracked Wax, substantially more severe conditions with attendanthydrocracking conversion are needed.

The catalyst employed in the hydroisomerization zone is described as anaphtha reforming catalyst, which typi cally comprises a Group VI metaloxide or a Group VIII metal hydrogenation-dehydrogenation component,desirably a noble metal, preferably platinum or palladium, associatedwith a porous refractory oxide carrier such as alumina, and which may bemoderately acidic or aciditied with a halide. Thus, a typical preferredcatalyst comprises essentially alumina promoted with a small amount,0.1-2 percent, of platinum metal and a small amount, less than 1percent, of chloride and/or fluoride. This includes well-known platinumreforming catalysts, but their action is quite different at theconditions used in the hydroisomerization zone. There is a netconsumption of hydrogen, and instead of forming aromatics fromnaphthenes, the essential reaction occurring appears to be one ofisomerizing moderately branched isoparafiins to highly branchedisoparafiins. The reforming catalyst is an active isomerizationcatalyst. Nitrogen and sulfur compounds may deactivate such a catalyst,and accordingly these heteroorganic compounds are substantially excludedfrom the hydrocracked wax feed. Instead of pure alumina or halidedalumina as the carrier or support, there may be used a moderately acidicalumina-silica cogel or coprecipitate containing more alumina thansilica. For example, good results have been obtained using a 2 percentpalladium catalyst on 82 percent alumina-l8 percent silica. Otheranalogous carriers and supports suitable for use will suggest themselvesto those skilled in the art. The silicaalumina materials containing moresilica than alumina, such as active cracking catalysts, do not appear tobe good supports for the catalysts because they are too strongly acidicand adversely affect selectivity for the isomerization of isoparafiins.

Good results have been obtained in the hydroisomerization step using aplatinum-alumina reforming catalyst containing only a small amount ofhalides, from to 1 weight percent total. The known noble metalisomerization catalysts containing upwards of 2 weight percent halideappear to be too acidic and have low selectivity at the conditionsemployed within the process of this invention, accomplishing lessisomerization and more hydrocracking and tending to become deactivatedmore rapidly. Improved results are obtained if the platinum reformingcatalysts are prereduced before use in the hydroisomerization, which canbe done by flowing hydrogen through the catalyst bed at 700-1 100 F.,especially at about 1000 R, for a few hours. Such a hydrogen treatmentcan also be used intermittently in the process to extend the catalystsactive life.

To improve selectivity for hydroisomerization in hydroisomerization zone41, there may be incorporated a prehydrogenation step in the mannerspecified in the aforementioned copending application Ser. No. 548,075.Similarly, to improve the quality of the isomerized lubricating oil andisomerized wax produced, there may be incorporated a post-hydrogenationstep at below 600 F. following the hydroisomerization.

The contacting of the hydrocracked wax and hydrogen with thehydroisomerization catalyst may be carried out manipulatively in themanners previously described with respect to the hydrocraclcing step. Ina similar manner, there is obtained a liquid oil eflluent of thehydroisomerization zone in line 42, which is distilled in facilities 43to remove the distillate fuel fractions produced boiling below about650750 F., and to recover an isomerized lubricating oil boiling rangefraction in line 46, i.e. boiling entirely above about 650750 F. Thisoil is then dewaxed to recover dewaxed isomerized lubricating oil and anisomerized wax fraction.

The dewaxing of the isomerized lubricating oil boiling range fractionmay be carried out in the same manner as used for dewaxing thehydrocracked lubricating oil boiling range fraction. In fact, all or aportion of the isomerized lubricating oil boiling range fraction in line46 may be passed via line 47 for dewaxing in admixture with all or aportion of the hydrocracked lubricating oil fraction in dewaxing zone23. The wax obtained in line 32 then may comprise a mixture ofhydrocracked wax and isomerized wax, and the properties includingviscosity index of the lubricating oil fractions obtained bydistillation of the dewaxed oil will be upgraded due to the inclusiontherein of the dewaxed isomerized oil. Preferably, at least a portion ofthe isomerized lubricating oil boiling range fraction is separatelydewaxed by passing through line 48 to dewaxing zone 49 in order torecover a dewaxed isomerized oil of ultrahigh viscosity index. Thedewaxing is controlled with reference to the pour point desired in theproduct lubricating oils, and there is thus obtained isomerized Waxwhich can be withdrawn as a product wholly or in part, or recycledwholly or in part to the hydroisomerization reaction zone. Recycling ofat least a portion of the isomerized wax to the hydroisomerization zone,controlling the relative proportions of fresh hydrocracked wax feed andrecycled isomerized Wax, can provide a method of adjusting the VI of thedewaxed isomerized lube oil fraction, for example to insure reaching anultrahigh VI of at least 130.

The dewaxed isomerized oil may be separated as by distillation intovarious grades of lubricating oil on the basis of viscosity and boilingrange. The dewaxed isomerized lubricatnig oil fractions so obtainedcharacteristically have much higher viscosity index than the dewaxedhydrocracked lubricating oils, but it is found that appropriatefractions of the isomerized lube oil and the hydrocracked lube oil canbe blended to obtain nearly any desired intermediate combinations ofviscosity and viscosity index. Also, the isomerized lube oil can beblended with straight run lube oil fractions to obtain upgradedproducts.

In the marketing of lubricating oils, it is frequently desired to offera slate of oils in various viscosity ranges having the same viscosityindex, for example to offer a neutral, a 400 neutral, and a 120 brightstock all having a viscosity index of 110. Such a situation is rarelyobtainable directly by the hydrocracking, as it is more frequently foundthat the lower viscosity light lubricating oil produced has a lowerviscosity index than the heavier high boiling lubricating oil fraction,or vice versa. By the present invention it has been found possible toproduce a slate of lubricating oils of a constant viscosity index in thevarious viscosity grades. Thus, in cases where one or more of thehydrocracked dewaxed lube oil fractions if recovered separately wouldhave too low a viscosity index to be readily salable, a portion of theisomerized lubricating oil boiling range fraction may be dewaxed inadmixture with the hydrocracketl lubricating oil fraction sufiicient toprovide a desired minimum viscosity index in the resulting blend ofdewaxed hydrocracked and isomerized oil. Another portion of theisomerized lubricating oil boiling range fraction may be dewaxedseparately to obtain an ultrahigh viscosity index dewaxed oil, and aportion of the dewaxed isomerized oil may be blended with a portion ofthe combined dewaxed isomized and hydrocracked oil, thereby providing aminimum viscosity index product, an intermediate viscosity indexproduct, and a high viscosity index product.

The possibility of distilling the hydrocracked lubricating oil boilingrange fraction and the isomerized lubricating oil boiling range fractionprior to solvent dewaxing the resulting cuts separately has already beenmentioned. In this context obviously portions of one or moredistillation cuts from the isomerized lubricating oil fraction couldthen be blended with corresponding distillation cuts of the hydrocrackedlubricating oil fraction for dewaxing in admixture. The possibility ofcombining the entire liquid oil effluent of the hydroisomerization zonein line 42 with the entire liquid oil eflluent of the hydrocracking Zone14 in line 15 for distillation in common facilities to recover a mixtureof hydrocracked and isomerized lubricating oil boiling range bottoms,has also been considered. This is feasible only if the entire bottomsfraction, or substantially all of it, would be dewaxed for recovery oflubricating oil fractions. If a substantial portion of the hydrocrackedlubricating oil boiling range fraction is withdrawn as by line 21 of thedrawing, there would be substantial loss of the hydroisomerized oiltherein.

The following example is illustrative of the practice of the inventionand further shows the unusual nature of the products obtainable thereby.

Example From propane-butane deasphalting of vacuum residua of mixedcrude oils there was obtained a deasphalted residual oil of 16 APIgravity, containing 6000 p.p.m. nitrogen and 1.2 weight percent sulfurwith a pour point of 105 F. Over 90 percent of the oil boiled above 800F. and over 80 percent of the oil boiled above 900 F. This oil washydrocracked severely as needed to obtain a gravity of 34 API in thewhole normally liquid oil efiiuent Table II presents inspections of thedeasphalted oil, the hydrocracked oil, the hydrocracked slack waxseparated from the hydrocracked oil, the hydroisomerized oil, and theisomerized wax separated from the isomerized oil.

TABLE II Weight Percent Gravity, API

Below 750- 900- Above 750 F 900 F. 1,000 F. 1,000 F.

Deasphalted Oil Fed to Hydrocraeker 16 2 18 2O 60 Hydrocracked Oil fromHydrocraeken 34 60 15 1O Slack Wax from Hydrocracked Oil. 35. 2 15. 718. 9 65. 4 Hydroisomerized Oil After Hydrogena. 40. 5 28. 7 34. 2 16. 621. 4 Hydroisornerized Wax 6. 3 26.0 21. 9 45. 8

by contacting with a 15% nickel sulfide-% tungsten sulfide (60%alumina-40% silica) catalyst at 815 F., 2400 p.s.i.g., 0.67 LHSV, withabout 5,000 s.c.f. H /bbl. The efiluent oil was freed of NH and H 8 anddistilled to recover a distillate fraction and a bottoms fraction, thelatter boiling entirely above 750 F. and amounting to 40 percent yieldfrom the deasphalted oil. The bottoms fraction had a pour point of +105F. and contained 20 p.-p.m. nitrogen. This lubricating oil boiling rangehydrocracked bottoms fraction was dewaxed to a pour point of 0 F. usinga methylethyl ketone/benzene solvent. The slack wax thereby obtained hada gravity of 35.2 API and contained 4 ppm. nitrogen and 15 p.-p.m.sulfur. This slack wax was hydroisomerized by contacting with a 0.5weight percent platinum on alumina catalyst at 770 F., 2600 p.s.i.g.,0.35 LHSV, with 10,000 s.c.f. H /bb1. In the same reactor, the efliuentof the hydroisomerization after contacting the platinum catalyst is thenpassed through a bed of 1 percent palladium on 80% alumina- 20% silicacatalyst at a lower temperature of 500 F. and higher space velocity of0.7'LHSV as a mild finishing hydrogenation treatment. Conditions in thehydroisomerization step were selected so as to obtain constant gravityin the product of 40 API. This coresponded to conversion of from 80 to86 percent of the hydrocracked wax to nonwaxy hydrcarbons. The waxy oilfrom the hydroisomerization and hydrogenation treatment was distilled toremove the approximately -30 volume percent distillates boiling below750 F and the isomerized lubricating oil boiling range fraction boilingabove 750 F. was then solvent dewaxed to a pour point of 5 F. using amethylethyl ketone/benzene solvent. The dewaxed isomerized oil was thendistilled into several narrow boiling range cuts for determination oflubricating oil inspections. The conditions used in the example and theresults obtained are summarized in the following tables.

Table I presents the conditions used in the hydrocracking of thedeasphalted oil and in the hydroisomerization and hydrogenation of thehydrocracked wax.

ill

Table III presents inspections of typical dewaxed lubricating oilfractions A and C recovered from the hydrocracked oil, typical dewaxedisomerized lube oil fractions B, D, and F recovered from the isomerizedoil, and representative blended oils obtainable therefrom. Also shown isa hydrocracked lube oil, E, obtained by separately hydrocracking a heavyoverhead gas oil from a residuum stripping operation, having a very lowVI, and the improved VI blend obtainable using the isomerized oil.

TABLE III Dewaxed Dewaxed I-Iydro- Hydroisom- Blended cracked crizedLube Oil Lube Oil Lube Oil 3 vols. A A B plus 1 vol. B

Viscosity, SSU at- F 144 81. 5 210 F". 42.3 3&5 40 Viscosity Index 85,90

9 vols. C C D plus 1 vol. D

Viscosity, SSU at 100 F 436 184. 6 393. 9 210 F 50. 9 48. 4 58. 4 X 97133 101 7 volsv E E F plus 3 Vols. F

Viscosity, SSU at 100 F 129. 7 103.8 118. 4 210 F 40. 88 41.02 40.89Viscosity Index 67. 5 98. 5 Oxidation Stability, Hours 5. 8 11.6 7. 65

Table IV presents additional inspections of dewaxed hydroisomerizecllube oils obtained from the hydroisomerization of hydrocracked Wax inthe foregoing example, prepared by blending appropriate cuts of thedewaxed oils boiling above 750 F. to obtain fractions having specifiedviscosities of 70, 100, and 200 SSU at 100 F.

TABLE IV Boiling Range, F 750-800 800-875 875-1, 00 1, 000+ Gravity,API. 41.1 39. 6 37. 8 35. 0 Viscosity at 100 F 71. 9 103. 8 206. 7 659Viscosity at 210 F 37. 24 41. 02 50. 4 85. 8 Viscosity Index, VI 130 140132 124 Viscosity Index, Extended,

VIE 140 Pour Point, F -5 Cloud Point, F +4 Aniline Point, F 292Oxidation Stability, Hrs. 12. 2 11. 0 11.2 11.2

, UV Lamp Test, Hr 100 100 100 100 In the above Table IV, VIE refers toviscosity index determined in the extended range, above 100, by the newmethod of ASTM D-2270. This is considered to indicate more accuratelythe suitability of the oils as ultrahigh VI multi-grade base oils ascompared to the old method of ASTM D-567. reported as VI. Particularlyto be noted in the above data are the very high viscosity indices in theisomerized lubricating oils and the nearly constant viscosity index ofabout 140 VIE in all the isomerized lube oil cuts boiling above 800 F.The pour points and cloud points are good and the oils have excellentoxidation stability and ultraviolet light stability. In the foregoingTables III and IV, Oxidation Stability is a measure of additiveresponse, and refers to the time required for a given volume of oil toabsorb one liter of oxygen from air bubbled through it at 340 B, whenthe oil contains both a commercial oxidation inhibitor and oxidationcatalyzers. A time of seven hours is considered excellent. The UV LampTest is a controlled sunlight simulator measuring the time for formationof a haze,

cloud, or sediment in the oil, as is, as an indication of lightstability. A value of 20 hours is considered very good in a typicalcommercial mid-content 150 neutral lube oil.

In a large installation processing 25,000 barrels of the deasphalted oilfeed as in the foregoing example, modified by including acid extractionof nitrogen compounds and recycling of isomerized wax, there would beobtained from the hydrocracking step about 18,000 barrels per day ofdistillate fuels and 8,000 barrels per day of hydrocracked oil boilingabove 750 F. About 4,000 barrels of this oil is withdrawn and passed toanother hydrocracker, or a catalytic cracker, or a thermal cracker, orblended into heavy fuel oil. The remaining 4,000 barrels is treated withhydrofluoric acid to lower the nitrogen content of the oil, leavingabout 3,900 barrels of clean waxy oil. Solvent dewaxing yields 1,200barrels of slack wax, and 2,700 barrels of dewaxed oil which isseparated into 900 barrels of 95 VI light neutral, 1,200

barrels of 98 VI heavy neutral, and 600 barrels of 100 VI bright stock.The 1,200 barrels of hydrocracked slack wax is catalytically isomerizedwith 210 barrels of recycle isomerized wax, distilled and dewaxed,yielding 430 barrels of distillates boiling below 750 F., 770 barrels ofdewaxed isomerized 130-140 VI lubricating oil, and the 210 barrels ofisomerized wax which is recycled. The dewaxed isomerized oils comprise230 barrels of 100 SSU neutral, 290 barrels of 200 SSU neutral, and 250barrels of 85 bright stock.

When the catalytic hydrocracking is operated at higher severity toobtain greater yield of distillate fuels, a higher viscosity index isobtained in the hydrocracked lubricating oil boiling range fractions andthe hydrocracked wax is more amenable to treatment in thehydroisornerization zone. Accordingly, less severe conditions can beused in the hydroisomerization to obtain a high yield of isomerizedlubricating oil with less production of distillate fuels therein.

Various alternatives and obvious modifications in the process of theinvention as exemplified herein will be apparent to those skilled in theart, and accordingly the appended claims are intended to include allsuch modifications as are embraced thereby.

We claim:

1. Process for producing lube oil which comprises: hydrocracking adeasphalted petroleum residuum boiling mostly above 800 F. and at leastpartially above 900 F. by contacting said residuum and hydrogen with asulfactive hydrocracking catalyst in a hydrocracking zone underconditions to convert at least 20 percent of said residuum todistillates boiling lower than the feed and at least 30 percent of theportion of said residuum boiling above 900 to distillates boiling below900 and with a hydrogen consumption of at least 500 s.c.f. per barrel ofresiduum; separating the oil effluent from said hydrocracking zone intofractions including a distillate fuel and a hydrocracked lube oilboiling range fraction; dewaxing a said hydrocracked lube oil boilingrange fraction, thereby obtaining a hydrocracked wax fraction of lownitrogen content; hydroisomerizing at least a portion of saidhydrocracked wax fraction by contacting said wax fraction with an activereforming catalyst containing 0-2 weight percent halide in ahydroisomerization zone under conditions to convert at least 20 percentof said wax fraction to distillates boiling below 750 F.; and separatingthe oil eflluent from said hydroisomerization Zone into fractionsincluding a distillate fuel and a hydroisomerized lube oil boiling rangefraction.

2. The process of claim 1 wherein said dewaxing is accomplished by aconventional solvent dewaxing procedure.

3. Process according to claim 1 wherein at least a portion of a saidisomerized lube oil boiling range fraction is dewaxed in admixture withat least a portion of a said hydrocracked lube oil boiling rangefraction.

4. Process according to claim 1 wherein said hydrocracked lube oilboiling range fraction is further treated to remove organic nitrogencompounds before dewaxing said fraction.

5. Process according to claim 1 wherein said reforming catalystcomprises platinum supported on alumina and contains no more than 1weight percent halide.

6. Process according to claim 5 wherein said hydrocracked lube oilboiling range fraction is further treated to remove organic nitrogencompounds prior to dewaxing said fraction, whereby said hydrocracked waxfraction contains less than 10 ppm. nitrogen.

References Cited UNITED STATES PATENTS 3,308,055 3/1967 Kozlowski 2081112,668,790 2/1954 Good et al. 260-68365 3,142,634 7/1964 Ireland et al.208-95 3,142,635 7/1964 Coonradt et al. 208ll1 3,230,164 l/l966 Williamset al. 208-89 3,268,439 8/1966 Tupmon et al. 208-412 ABRAHAM RIMENS,Primary Examiner.

DELBERT E. GANTZ, Examiner.

Disclaimer 3,365,390i0Za1"/c J. Egan, Piedmont, and Robert J. White,Pinole, Calif. LUBRICATING OIL PRODUCTION. Patent dated Jan. 23, 1968.Disclaimer filed Dec. 11, 1968, by the assignee, Chevron ReseamhCompany. Hereby enters this disclaimer to claim 6 of said patent.

[Ofiicial Gazette April 29, 1.969.]

